In LTE (Long Time Evolution) and previous wireless communication system, a cell only has a carrier; the max. Bandwidth in LTE system is 20 MHz, as shown in FIG. 1. Since LTE system is single-carrier system, source eNB only provides information of a cell to target eNB during handover judgment for accepting judgment of target side eNB.
In LTE-A (LTE Advanced) system, the peak rate is greatly improved compared with LTE, which is required to be 1 Gbp at downlink and 500 Mbps at uplink. Only using the carrier with maximum bandwidth of 20 MHz can hardly achieve the requirements of peak rate. Therefore, LTE-A system needs to expand the bandwidth available to terminal, thus the introduction of CA (Carrier Aggregation) technology, that is, aggregate several continuous or discontinuous carriers under the same eNB (evolved Node-B,) and serve UE (User Equipment), so as to provide the required rate; thus these aggregated carriers are also called CC (Component Carrier). Each cell can be a cell, and those cells (CCs) under different eNB cannot be aggregated. To ensure UE of LTE can be work under each aggregated carrier, each carrier cannot exceed 20 MHz at most. CA technology of LTE-A is shown in FIG. 2, where there are 4 carriers that can be aggregated under the eNB of LTE-A shown, and the eNB can perform data transmission on 4 carriers and UE simultaneously, to improve system throughput.
In LTE-A system, UE can be aggregated on multicarriers at the same time to carry out signalling scheduling and service transmission. Viewed from resource allocation, allocation of some uplink resource (including channel quality Indicator (CQI), dedicated scheduling request (DSR) and uplink HARQ feedback (ACK/NACK) have been restricted on certain uplink carrier in standard discussion at present and concept of primary component carrier (PCC) has been defined, viz. bind the restriction on three uplink resource allocations introduced by RAN1 on primary component carrier. Among multicarriers aggregated of UE, carriers other than primary component carrier are secondary component carrier (SCC). Primary component carrier is selected at UE level, viz. all UE of the system are not required to use the same primary component carrier. In addition, uplink and downlink carriers composing primary component carrier are required to meet corresponding relation indicated in system information SIB2. In carrier aggregation system, UE can aggregate multiple cells to work at the same time. In discussion regarding measurement at present, concept of Pcell and Scell is defined aiming to multiple cells with UE aggregated, which is corresponding respectively to primary component carrier (PCC) cell and secondary component carrier (SCC) cell the UE aggregated.
However, during multicarriers handover, when UE is switched from source eNB toward target eNB, corresponding solution of how source eNB carries indication information that target eNB selects Pcell cell and Scell during handover has not been provided in present technology.